1. Field of the Invention
The invention generally relates to analytical systems and methods for automated sampling and measuring of various parameters for environmental purposes, water management, process optimization and early warning system for monitoring, management and mitigation efforts. More particularly it relates to an automated system for the periodic profiling of water bodies like lakes, rivers, reservoirs and estuaries and delivering the test results to a remote computer using a communication system.
2. Description of Related Arts
The invention may be used for the remote measuring of environmental parameters using one or several autonomous stations having a deployment platform with a power supply system, controller unit and a communication system, wherein said deployment platform connected through an underwater cable to the sampling device made as a variable buoyancy profiler with a sensor package.
In the prior art, an autonomous oceanographic profiler has been developed for collecting information about water quality. U.S. Pat. No. 5,283,767 describes a profiler carrying a sensor package and changing buoyancy using a mechanical trim piston. The mechanical piston system provides near 50 cm3 of profiler volume change. This profiler has no permanent connection with the base station and cannot send real time data.
Another device is the variable buoyancy ballast and flotation unit described in U.S. Pat. No. 5,655,938 or the sonobuoy according to U.S. Pat. No. 5,224,074, which use valves and compressed air to change the buoyancy of the submersible units. For extended operation the system must be recharged.
The buoyancy control system, which is described in U.S. Pat. No. 5,379,267 is also capable of being moved vertically, but this system operates by discharging measured quantities of either a heavy or light liquid. For extended operation the system also has to be recharged.
The remote sensing station that is described in U.S. Pat. No. 5,816,874 has a depth control housing with a sealed interior chamber and a pump providing water inside the interior chamber to adjust buoyancy. This system has a limited operational time and depth range because air inside of said chamber is not separated from the water therefore during pumping cycles air will be gradually dissolved in the water, which is pumping in and out. Because the air pressure inside the chamber is low and becomes even lower during operation the pump is required to overcome the external water pressure at the maximum depth. Such profiler uses electrical power with low efficiency and cannot work at a depth where water pressure is higher than the maximum pressure of the pump. A guide line for guiding the profiler described in this patent provides additional friction during profiler movements that increases power consumption and adversely effects the accuracy of the system.
The method and apparatus for controlling the depth of submergence of an underwater vehicle that is described in U.S. Pat. No. 3,675,607 works with positive buoyancy of a submerged housing but, according to the patent, it should be constant at the different depth and lower by the absolute value then negative buoyancy of the cable and a depth control body. Precise depth control is obtained by controlling the length of the cable. This method and apparatus requires constant controlling of the cable length, a large power budget, and a depth control body operating with a negative buoyancy and laying on the bottom of the water body.
The buoyancy compensators described in U.S. Pat. Nos. 3,820,348, 4,114,389, 5,551,800 need pressurized air for their operation, and all of them are designed to increase buoyancy when the buoyancy compensator moves from the water surface to the deep water.